1. Field of the Invention
The invention relates to laser beam optics in a robot link, wherein a first beam path of a first working laser beam is to be arranged in the longitudinal axis of the robot link, which first laser working beam is deflectable at an end facing the workpiece into an axis-parallel second beam path, and wherein a third beam path of a second working laser beam is to be arranged axis-parallel to the first beam path of the first working laser beam in the robot link.
2. Description of the Related Art
Optics with the aforementioned features are known from EP-A-0 901 875. The first working laser beam of the known robot is guided to an attachment unit which has the task of deflecting the first laser beam from the first beam path into the second beam path which is axis-parallel to the first beam path. In the known laser robot a third beam path of a second working laser beam can be provided, in particular, such that it is to be arranged parallel to the first beam path of the first working laser beam. However, this is possible only when the attachment unit for deflection of the first working laser beam is removed. This is so because the attachment unit projects into the second and also into the third beam path since these two aforementioned beam paths are aligned with one another. Accordingly, when different types of working laser radiation are to be employed, for example, a CO2 laser radiation or a diode laser radiation, a retrofitting of the robot link must be carried out during which the attachment unit is to be either mounted or demounted. This is complex and requires a subsequent adjustment. Moreover, it is not possible to operate the robot simultaneously with two laser beams.
It is an object of the present invention to improve laser beam optics with the aforementioned features such that they are suitable for an alternating use of different working laser radiation without requiring retrofitting, and primarily are suitable for the simultaneous use of two different working laser radiations.
In accordance with the present invention, this is achieved in that in one of the beam paths of the first working laser beam two optical elements are successively arranged which are transmissive for the working laser beam in the direction toward the workpiece and which are adjusted to one another in the sense of a compensation of a beam displacement, and in that the second working laser beam is guided to the second one of the two optical elements and can be reflected by it toward the workpiece.
It is important in regard to the invention that by means of the laser beam optics two working laser beams can be combined such that both can perform alternatingly or together the desired machining of a workpiece in one working step. In this connection, the working laser beams should be able to have different radiation, respectively, i.e., radiation having different radiation parameters. The first working laser radiation should be, for example, CO2 radiation and the second working laser radiation should be Nd:YAG radiation. It is to be taken care of that the laser beam optics can combine the beams error-free. This is achieved particularly in that the first working laser beam passes through optical elements successively which are adjusted relative to one another in the sense of avoiding beam displacement. As a result of this, the combination location of the laser beam optics is constructively fixed. It is not required to provide other optical measures in order to compensate the beam displacement. Otherwise, it would be required to mount components at a location downstream where no space is available within the robot link for the purpose of performing compensating measures.
An advantageous embodiment of the laser beam optics is characterized in that the first optical element is a beam-transmissive compensation plate, that the second optical element is a reflector plate, which is also beam-transmissive but reflects the second working laser beam, and that the entry symmetry axis of the compensation plate and the exit symmetry axis of the reflector plate are aligned. In this way, the beam displacement can be compensated by two plates whose refractive properties are identical and which act relative to one another in a compensating way with regard to the beam displacement.
In this connection it is to be preferred that the two optical elements are arranged at an angle to one another which compensates a beam displacement.
Instead of plates, all optically active components can be employed with which a beam compensation can be eliminated. In this respect, it can be expedient to configure the laser beam optics such that at least one optical element is comprised of two prisms which act optically as a plate.
When the two optical elements are transmissive for CO2 laser radiation, conventional plate materials can be used which, with respect to 10.6 xcexcm radiation of a CO2 laser, are well researched and established, for example, zinc selenide.
It is then advantageous and necessary to configure the laser optics such that the second optical element is highly reflective for the Nd:YAG radiation.
In order to achieve a substantially loss-free radiation passage, the laser optics can be configured such that the two optical elements are coated with an anti-reflective coating at the entry side and exit side for the beams. An anti-reflective coating prevents radiation losses at the entry and exit surfaces of the optical elements.
Moreover, the laser optics can be configured such that the second optical element is coated on a reflector surface facing the second working laser beam so as to be highly reflective for the second laser beam. Such a highly reflective coating is particularly required when radiation losses of the second laser beam are to be prevented. Such radiation losses would have to be expected particularly when the second optical element were radiation-transmissive even if only for a radiation of a different wavelength.
An expedient configuration of the laser optics is achieved in that for feeding the second working laser beam to the second optical element a deflection mirror is present which is parallel to the reflector surface of the second optical element. This achieves a right angle deflection of the second laser beam relative to the second beam path.
A constructively particularly advantageous configuration of the laser optics can be achieved in that the two optical elements and, if needed, a deflection mirror are arranged in a single housing. This provides a modular unit which ensures a fixed correlation of the optical elements relative to one another independent of the assembly of this modular unit on the robot link. The housing can be robust so that the configuration and function of the two optical elements are not endangered, in particular, during mounting of the housing on the robot link.
In another embodiment of the invention, the laser optics can be embodied such that a housing having a beam exit is mounted on an end face of the robot link facing the workpiece and is provided at the end facing away from the workpiece with a first beam entrance for the first working laser beam and a second beam entrance for the second working laser beam. This provides a simple and reliable attachment of the housing as well as a matching correlation of the beam entrances relative to the beam paths.
The laser beam optics can have a configuration such that a beam displacement module is attached to the housing in the area of its first beam entrance and has a first displacement mirror in the area of the first beam path and a second displacement mirror at the beginning of the second beam path. The deflection of the first working laser beam is realized accordingly by means of a special component which is configured especially with regard to its deflection or displacement task and can be attached additionally to the housing that contain the two optical elements.
A special configuration of the laser beam optics can be provided in that the housing in the area of the second beam path has a mounting cutout in which an element support comprising the optical elements is mounted. The element support enables particularly a matched arrangement of the elements relative to one another. As for the rest, the housing can be configured independent of the element support, and it is only necessary that the housing in the area of the attachment of the element support has a precise enough configuration in order to fulfill the optical requirements with regard to avoiding beam displacement.
The laser beam optics can moreover be improved in that the deflection mirror optically arranged upstream of the second optical element is secured on an exterior housing wall which is parallel to a wall of the mounting cutout facing the workpiece. The exterior wall of the housing and the wall of the mounting cutout can be manufactured parallel with high precision. This is advantageous in regard to the optical precision of the beam combination.
In order to make the laser beam optics suitable for use with such a robot link, which has arranged downstream further links of a robot hand, the laser beam optics can be configured such that the second beam path and a fourth beam path, beginning at the reflecting optical element and common to both laser beams, are arranged in a plane, defined by the longitudinal axis of the robot link and a pivot axis perpendicular thereto of an additional robot link, and spaced at a predetermined spacing from the longitudinal axis of the robot link. As a result of this, the beam path common to both working beams can be located in the vicinity of an outer periphery of the robot link, components required for the downstream links can be arranged in its longitudinal axis, and only one single mirror is required for beam deflection into the pivot axis of the additional robot link.